Drilling machine



Sept. 12, 1961 J. GERENTES DRILLING MACHINE 4 Sheets-Sheet 1 Filed Oct.30, 1957 lllll III lllll H Sept. 12, 1961 J. GERENTES 2,999,550

DRILLING MACHINE Filed Oct. 50, 1957 4 Sheets-Sheet 2 1/////A//////////////////////A'|||||||l||||||llIllIlllIlllllllml|||||[IllllllllllllllllllllllllllllllllllllllllllIIIIllllllllllllllllllllllIIIIIIIIIIIIIIIIIIWWEWWMWWIWIWW Sept. 12, 1961 J. GERENTES DRILLING MACHINE 4 Sheets-Sheet3 Filed Oct. 50, 1957 mmmmmm E Sept. 12, 1961 .1. GERENTES DRILLINGMACHINE 4 Sheets-Sheet 4 Filed Oct. 30, 1957 W i W a W mo bk; eww MIWWOm1 ,0 6 e i a w. @LW M W .n I w MAW w a V.

Z h m F FM P E H 2,999,550 DRILLING MACHINE Jean Gerentes,Saint-Etienne, France, assignor to Constructions Electro-Mecaniques deSaint-Etienne (Ancienne Usine Wageor), Saint-Etienne, France, acorporation of France Filed Oct. 30, 1957, Ser. No. 693,475 Claimspriority, application France Oct. 31, 1956 1 Claim. (Cl. 175-33) Thepresent invention relates to variable-feed electric drilling machines.

The applicant has already proposed a type of drilling machine in whichthe drill-bit is rotated by a main motor whereas its longitudinalmovements result from the action of this main motor and of an auxiliaryreversible motor, the main motor driving, in addition to thebit-carrying shaft, one of two members consisting of a nut and screw,the other of these two members being driven by the auxiliary motor, sothat feed of the bit results from the difierence between the rotationalspeeds of the screw and nut. Further, these motors have differentmechanical characteristics (torque C-speed N), that is dilierent slips,the slip of the aum'liary motor being the greater, which is easilyobtained with a squirrel-cage asynchronous motor by increasing theresistance of the cage. Thus, as the developed torques are a function ofthe hardness of the rock being drilled, the difierence in the speeds ofthe two driven members decreases when rock hardness increases and thisreduces the feed and reduces the load on each of the two motors.

For example, if the auxiliary motor drives the faster of said twomembers at a speed N and the main motor the other member at a slowerspeed N the feed of the drill-bit is a- 1) XP where p is the lead of thescrew.

By construction, when the hardness of the rock increases, the difference(N -N decreases, since, as the torque increases for each of the motors,the slip of the auxiliary motor increases much more rapidly than that ofthe main motor.

However, it could occur that in very marly ground where there isconsiderable friction on the periphery of the drill-bit or there isdifliculty in evacuating the drilled away matter, the speed N ofrotation of the main motor decreases considerably as a result of thehigh load. Thus, N decreases much more rapidly than N so that when (N -Nincreases instead of decreasing the speed of drill feed increases whichtends still more to increase the load and thus still more throws thesystem out of equilibruim. Wedging could occur and the considerableforces developed could cause the destruction of the component parts.

The object of the invention is to remedy this disadvantage.

The invention provides an electric drilling machine of theaforementioned type, characterised in that it is so arranged as tocomprise a plurality of speed ranges and is combined with a controldevice permitting an automatic speed range change in accordance with thetype of ground being drilled.

In a preferred embodiment, the auxiliary motor comprises at least twoinductance or stator windings having a different number of poles.

If, for example, the auxiliary motor comprises two windings havingrespectively four and six poles, when operating on four poles, the drillfeed is (N -N X p, whereas when operating on six poles, it is only dStates Patent Q Preferably, the supply circuits of the sole winding ofthe main motor and the windings of the auxiliary motor are combined withan electromechanical control device comprising manually-operatedcontactors permitting a manual control of the drill feed, and anautomatic control means permitting an automatic change in the speed ofthe auxiliary motor, and thus in the longitudinal displacement of thedrillbit, in accordance with the intensity of the current consumed bythe main motor.

Advantageously, this automatic control means could be an overcurrentrelay disposed in the main motor supply circuit and the electric controlcircuits are so arranged that the winding corresponding to the greaternumber of poles of the auxiliary motor is put in circuit as soon as agiven maximum intensity is reached in the main motor supply circuit.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawings, towhich the invention is in no way limited.

In the drawings:

FIG. 1 is a diagrammatic view in elevation, with a part cut away, of adrilling machine embodying the invention;

FIG. 2 is a partial longitudinal sectional view on an enlarged scale ofthe auxiliary motor and a part of the main motor;

FIG. 3 is a diagrammatic front View, with a part of the wall cut away,of th erelay box of the drilling machine;

FIG. 4 is a side view of the relay box, and

FIG. 5 is a diagram of the electrical connections.

In the embodiment shown in FIGS. 1 to 3, the drilling machine comprisesa stand comprising two parallel longitudinal roiled-section members 10along which is movable an electrical motor M whose output shaft 12 isconnected to a drill-bit carrier 13 by a gear train 14-, 15, 16, 17; thegears 15 and 16 are keyed to an idle shaft 18 to which is secured athird gear 19. The carrier 13 carries the drill-bit or tool 20 which isguided by a fixed bushing 21 and a movable bushing 22.

Fixed at the rear end of the stand is an auxiliary motor M whose outputshaft 23 (FIG. 2) is connected, by means of a speed-reducing gear train24, 25, to the end of a longitudinal screw 26. The latter is fixed asconcerns movement in the direction of its axis but it is journalled inthe stand. Screw-threadedly engaged thereon is a nut 27 which isjournalled in the housing of the motor M so as to drive the latter alongthe screw 26 in accordance with the difference between the speeds N andN of the screw and this nut, the latter being driven by the motor Mthrough the gear 19 meshed with a gear 28 which is coaxial and rigidwith the nut.

The motors M and M are three-phase motors and are so designed that theslip of motor M is greater than that of the motor M their slips beingpreferably about 5 and 15% respectively. The motor M having the greaterslip, could be in particular a squirrel-cage asynchronous motor whereinthe slip is a function of the resistance of the bars of the cage and isthe greater as this resistance is higher.

The main motor M is a motor having a single winding, as can be seen at29 in FIG. 2, whereas the motor M: has two windings 3i) and 31 having,for example, four and six poles corresponding to speeds N andrespectively.

cables 35 connect the box 33 to the drilling machine and the two cables36 connect this box to the box 32. Each cable has of course severalconductors.

I It will be observed from the diagram shown in FIG. that the variousrelays are designated by roman reference characters I to VIII and thecorresponding contacts by arab reference characters 1 to 7; the variouscontacts pertaining to the same relay are distinguished by an exponentcharacter. Thus contacts 2 2*, 2 are provided for the relay II.

The push button contactors are designated by capital letters, A, B F.

The power supply is three-phase and the supply cable 34 thereforecomprises three conductors L L and L each of which corresponds to aphase.

The motor circuits will first be described.

Main motor M .-The three phases, 40, 41 and 42 are star connected; theconductor 40 is connected to the phase L through the contact 2 (acontact of the relay II); the conductor 41 is connected to the phase Lthrough the contact 2 and the conductor 42 is connected to the phase Leither through the coil 43 of the overcurrent re lay I or through abypass contact 7, this coil 43 and this contact being both seriesconnected with the contact 2.

Auxiliary motor M .-The high speed windings 44, 45 and 46 are starconnected and the same is true of the windings 47, 48 and 49corresponding to the low speed.

The windings 44 and 45 are connected to the phases L and L through thecontacts 4, 5 and 5 4 respectively. The winding 46 is connected to thephase L; by either one of two contacts 4, 5.

The windings 47, 48 and 49 are connected to phases L L and L throughcontacts 3 3 and 3 respectively.

Description will not be given of the initial excitation circuits andthen the maintenance circuits of the relays II to VIII (theovercurrent-relay I circuit has been described hereinbefore). Theserelays having coils 50 to 56 are combined on the one hand with thefollowing push button contactors biased by springs:

A corresponding to stoppage of the drilling,

B corresponding to the start of the drilling,

C corresponding to a reduced drill feed,

D corresponding to stoppage of the drill feed,

E corresponding to the return rearward movement of the drill-bit byreversing the direction of rotation of the motor M power being suppliedto the windings for operation at normal speed.

F corresponding to the two contacts F and F of the manually controlledpassage from drill feed at reduced speed to feed at normal speed.

Said relays having coils 50 to 56 are furthermore combined with a switchG corresponding to the end of forward drill travel and switch Hcorresponding to the end of rearward travel. These switches are at thebase of the diagram shown in FIG. 5 and near the ends of the stand 10shown in FIG. 1.

The relay circuits are as follows:

Relay I.-This relay is series connected with one of the branchconductors of the motor M Relay II corresponding to the start ofdrilling by way of its contacts 2*, 2 and 2. Its main supply circuit is:phase L stop contactor A, contactor B corresponding to the start ofdrilling, point a, the winding 50, switch H corresponding to the end ofrear drill travel, and phase Its maintenance circuit is: L switch A,point 5, contact 2 winding 50, switch H, phase L Relay III controllingthe drill feed at reduced speed through the contacts 3*, 3 and 3. Itsexcitation circuit is: L reduced speed drill feed contactor C, winding51, contact 5 end of forward travel switch G, L

Its maintenance circuit is: L contactor D corresponding to stoppage ofthe forward drill feed, point c, contacts 4 6, 4 first contact F of thedouble contactor F, winding 51, contact 5 end of forward travel switchG, L

Relay IV controlling drill feed at normal speed through the contacts 44*, 4. Its excitation circuit is: L the second contact F of the doublecontactor F, point d, cont-actor 3 winding 52, contact 5 switch G, L

The maintenance circuit is: L contactor D, point c, contacts 4 6 3winding 52, contact 5 switch G, L

Relay V controlling the reverse drill travel. Its excitation circuit is:L contactor E corresponding to reverse operation, point e, contacts 3e,4 53, reverse operation switch H, L whereas its maintenance circuit isby way of the contact 5*.

Relay VI.--This relay is an auxiliary relay whose excitation circuit is:L stoppage contactor A, point b, contacts 8 2', winding 54, contact 5end of forward travel switch G, L

RELAY VII.-This relay is adapted to short-circuit the relay I by closingthe contact 7 Its excitation circuit is: L the contact P of the doublecontactor F, point d, contact 3 winding 55, end of reverse travel switchH, L

Relay VIII.--This is :an auxiliary relay whose excitation circuit is: Lstoppage contactor A, contactor corresponding to the start of drillingB, contact 1 of the relay I, contact 3 winding 56, contact 5 end offorward travel switch G, L

The following table illustrates the positions of the various contactswhen the windings of the relays are not energized, the conditions ofthese contacts being reversed after energization of the relays.

Table Winding not energized Winding N o. of relay of Relay ContactsContacts open closed The machine operates in the following manner:

When the machine is inoperative, the contactors and contacts are in thepositions in the diagram shown in FIG. 5.

Elements A, D, F 7 8*, 3 6', 4 3, 4 3, 1, 5 are closed. The switches Gand H are also closed and the carrier 13 is shown to be in anintermediate position in its travel (FIG. 1).

All the other contactors and contacts are open.

To perform a drilling operation the following successive operations areeffected:

1) The push button of the contactor B is depressed. The motor M isthereby started. As the contactor A is closed, the relay II is excitedthrough the circuit L A, B, 50, H, L and maintained excited when thecontactor is released by its maintenance circuit through the contact 2which is closed by the initial excitation. The contactor A remainsexcited until the end of one operational cycle. The auxiliary relay VIIIis excited at the same time and opens the contact 8 which preventsexcitation of the auxiliary relay VI.

(2) The push button C, corresponding to the start of forward drill feedat reduced speed, is depressed.

The relay III is excited through the circuit L C, 51, 5 G, L andmaintained excited through the circuit L D, c, 6, 4 F 51, 5 G, L Therelay III closes its contacts 3 3 3 and the motor M starts up at reducedspeed.

Simultaneously, supply of current to the relay VIII is stopped by theopening of the contact 3 which results in the excitation of the relay VIowing to the closure of the contact 8*; this ensures maintenance of theexcitation of the relay III through the circuit: L D, c, 6 (closed bythe excitation of the relay VI), 4 F 51, 5 G, L

It should be noted that there will be no trouble if, having pushedbutton B (operation 1) thereby starting the motor M one fails to pushbutton C (operation 2). In fact, either of two cases will occur:

Either the reversible mechanical system (screw 26, auxiliary motor M isfree; in this case, the nut 27 drives the screw 26 at its own speed, andsince there is no relative screw-nut speed, the drilling motor M doesnot move; or, in a more frequently occurring case, the screw 26 remainsimmobilized by friction; in this case, the nut is unscrewed from thescrew, the drilling aggregate (M 27, 20) moves back, and stopping wouldbe effected by the opening of switch H corresponding to the end ofrearward travel if the operation has not acted in the meantime.

(3) The push button F corresponding to a more rapid feed of thedrill-bit is depressed and this closes the contact F and opens thecontact F This results in:

(A) either normal operation of the machine with the high speed drillfeed. The relay II is still excited by its maintenance circuit. Therelay III is no longer excited owing to opening of the contact F Therelay IV is excited through its circuit L F 3 52, 5 G, L which closes inparticular the contacts 4*, 4 4 supplying cur rent to the windings 44,45, 46 of the motor M The relay VII is put in action by closure of thecontact 3 which prepares the automatic operation by opening the contactor sign and the drill-bit moves rearwardly at high speed z-l- 1) XP- (5)The feed stopping contactor D is depressed and all the relays except therelay II are excited. The main motor M is the only one that rotates.

(6) The stop contactor A is depressed and all the relays cease to beexcited. The two motors M and M are stopped.

Briefly, the start of the drilling operation is obtained by depressingthe contactor B, depressing the contactor C results in reduced speeddrill feed and then in depressing the faster contactor F normal speed isobtained at the same time as the short-circuit 7 of the operating coilof the relay I is broken, which permits this apparatus to operate whenthe maximum operational intensity is reached so as to automaticallycause the drill feed to resume its reduced speed. It will be understoodthat it is then possible to return to normal operation by once moredepressing the contactor F. If the consumed current intensity remainsless than the pre-determined intensity, this speed is maintained;otherwise, the machine returns to the reduced speed position.

The end of travel switches G and H perform their normal functions at theend of the forward drill feed and at the end of the drill returnmovement by opening the relay circuit s.

The following table shows the various positions of the relays accordingto the contactor depressed. The letter X indicates an operative relay.

Oontactors Reference Characteristics Stoppage of drilling. Start ofdrilling.

Automatic operation ormal operation and preparation of automaticoperation.

when maximum current intensity is reached. Return to reduced speed feedas obtained by depressing contractor O.

7 which excites the relay 1. The relay VIII is once more put into actionthrough the circuit L A, b, F, a, 1 3, 56, 5 G, L The relay VI ceases tobe excited owing to the opening of the contact 8 The relay IV ismaintained excited, when the contact F is no longer depressed, by itsmaintenance circuit L D, c, 4 6 3 52, 5 G, L

(B) or an automatic return to the low speed drill feed if the load onthe motor M reaches a given maximum. At this moment, the relay Ioperates and opens the contact 1 The relay VIII ceases to be excited.The relay V1 is put back into action by closure of the contact 8 Therelay IV corresponding to high speed drill feed ceases to be excitedowing to opening of the contact 6. The relay III corresponding to thelow speed drill feed is put back into action by closure of the contacts6 and 4 and then is once again supplied with current through itsmaintenance circuit. The drilling operation proceeds at low speed drillfeed.

(4) The reverse drill travel contactor E is depressed. The motor Mcontinues to rotate since the relay II is still excited.

The relay V is excited through the circuit E, e, 3, 4 53, H, L and itcloses the contacts 5, 5 5, which permit the motor M to rotate at highspeed but in the direction opposite to that corresponding to drilling.

Maintenance of the circuit current is ensured by closure of the contact5 The speed M changes the direction Although a specific embodiment ofthe invention has been described, many modifications and changes may bemade therein without departing from the scope of the invention asdefined in the appended claim.

Thus, the auxiliary motor M could have more than two windings, in whichcase there would be more than two ranges of variable speed drill feeds.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is:

A variable feed drill comprising a drilling tool, a longitudinallymovable drilling tool carrier, a three-phase main motor coupled to androtating said tool, a threaded member, a nut member engaging thethreaded member, one of said members being longitudinally fixed, theother of said members being coupled to said carrier for moving the same,said three-phase motor rotating said other member, an auxiliaryreversible motor rotating said one member whereby said carrier is movedin accordance with the difference between motor speeds, the auxiliarymotor being a three-phase motor comprising at least two field windingsincluding a different number of poles so that said auxiliary motor hasat least two speed ranges each corresponding to one of said windings,the auxiliary motor having a greater slip than the first said motor andhaving a plurality of speed ranges, a control device independent of andcoupled to the auxiliary motor for commutating the field windingsthereof thereby automatically changing the range in accordance with thetype of substance to be drilled, said control device comprising anelectro-mechanical control including manually operated contactors, saidcontrol being coupled to said motors for a manual control of themovement of the carrier and of the speed range of the auxiliary 5 motor,an over-current relay disposed in the current supply of the first saidmotor, and circuits coupled to the auxiliary motor and relay, said relayactuating the winding of the auxiliary motor having the larger number ofpoles when current in the first said motor achieves a pre- 10 determinedlevel.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS France Dec. 30, 1953

